CXCR4 has a dual role in improving the efficacy of BCMA-redirected CAR-NK cells in multiple myeloma

Front Immunol. 2024 Jun 24:15:1383136. doi: 10.3389/fimmu.2024.1383136. eCollection 2024.

Abstract

Multiple myeloma (MM) is a plasma cell disease with a preferential bone marrow (BM) tropism. Enforced expression of tissue-specific chemokine receptors has been shown to successfully guide adoptively-transferred CAR NK cells towards the malignant milieu in solid cancers, but also to BM-resident AML and MM. For redirection towards BM-associated chemokine CXCL12, we armored BCMA CAR-NK-92 as well as primary NK cells with ectopic expression of either wildtype CXCR4 or a gain-of-function mutant CXCR4R334X. Our data showed that BCMA CAR-NK-92 and -primary NK cells equipped with CXCR4 gained an improved ability to migrate towards CXCL12 in vitro. Beyond its classical role coordinating chemotaxis, CXCR4 has been shown to participate in T cell co-stimulation, which prompted us to examine the functionality of CXCR4-cotransduced BCMA-CAR NK cells. Ectopic CXCR4 expression enhanced the cytotoxic capacity of BCMA CAR-NK cells, as evidenced by the ability to eliminate BCMA-expressing target cell lines and primary MM cells in vitro and through accelerated cytolytic granule release. We show that CXCR4 co-modification prolonged BCMA CAR surface deposition, augmented ZAP-70 recruitment following CAR-engagement, and accelerated distal signal transduction kinetics. BCMA CAR sensitivity towards antigen was enhanced by virtue of an enhanced ZAP-70 recruitment to the immunological synapse, revealing an increased propensity of CARs to become triggered upon CXCR4 overexpression. Unexpectedly, co-stimulation via CXCR4 occurred in the absence of CXCL12 ligand-stimulation. Collectively, our findings imply that co-modification of CAR-NK cells with tissue-relevant chemokine receptors affect adoptive NK cell therapy beyond improved trafficking and retention within tumor sites.

Keywords: BCMA; NK cells; adoptive T cell therapy; chemokine receptor CXCR4; chimeric antigen receptor; multiple myeloma.

MeSH terms

  • B-Cell Maturation Antigen* / genetics
  • B-Cell Maturation Antigen* / immunology
  • B-Cell Maturation Antigen* / metabolism
  • Cell Line, Tumor
  • Chemokine CXCL12* / metabolism
  • Cytotoxicity, Immunologic
  • Humans
  • Immunotherapy, Adoptive* / methods
  • Killer Cells, Natural* / immunology
  • Killer Cells, Natural* / metabolism
  • Multiple Myeloma* / immunology
  • Multiple Myeloma* / therapy
  • Receptors, CXCR4* / genetics
  • Receptors, CXCR4* / metabolism
  • Receptors, Chimeric Antigen* / genetics
  • Receptors, Chimeric Antigen* / immunology
  • Receptors, Chimeric Antigen* / metabolism

Substances

  • Receptors, CXCR4
  • B-Cell Maturation Antigen
  • CXCR4 protein, human
  • Receptors, Chimeric Antigen
  • Chemokine CXCL12
  • CXCL12 protein, human
  • TNFRSF17 protein, human

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was funded in part by a sponsored research program from Fate Therapeutics (San Diego, CA). HE was supported by an MD student stipend from Berliner Krebsgesellschaft, Berlin, Germany. MM was funded by a PhD student stipend from DAAD (Germany) and further supported by the BSIO program at Charite-University Medicine, Berlin, Germany. The funding organizations had no influence on the study design, conduct of the study, data generation or data interpretation.